What is going on? Look at what my multimeter gave me for resistor readings. I made doubly sure I was only touching the legs of the resistor. RED = multimeter shows wrong value. BLUE = BOM value. I re-tested R17 multiple times, even testing it from the bottom of the PCB. All resistor markings are correct, but the value isnt?!?!?!

What's more interesting? The PCB I have not wired (my other waveshaper) shows the correct values on my multimeter!

Edit: On my second waveshaper, the multimeter shows 45.7K for the 2.2M value (R55). That's the only resistor that shows the wrong value.

When the resistors are soldered in, they will be connected to other components that can and will give you readings different than the nominal value.

For the really basic example, if I have a 100k resistor that is mounted parallel to the CW and CCW legs of a 100k pot (this is not a real world example), if I try to measure it I will read 50k--because it's seeing the two 100k's in parallel.

There's not likely to be anything QUITE that simple in this circuit, but I have never been able to read resistance reliably once the circuit is soldered together. It *is* dependent on the details of the circuit, however....

What is going on? Look at what my multimeter gave me for resistor readings. I made doubly sure I was only touching the legs of the resistor. RED = multimeter shows wrong value. BLUE = BOM value. I re-tested R17 multiple times, even testing it from the bottom of the PCB. All resistor markings are correct, but the value isnt?!?!?!

like elmegil said, measuring resistors in circuit is not that simple, actually. it might be that there are resistances in parallel that you don't see at the first glance.

Quote:

What's more interesting? The PCB I have not wired (my other waveshaper) shows the correct values on my multimeter!

Yeah, I think my next step is to wire my other X-4046 VCO and put this one (the one we were debugging) through an oscilloscope to ensure the DC trimmers are correct. I do want to correct the weak sine signal. I'll have to debug that later. I know Dave Brown does debugging. Is there anyone else I might ask to look at my waveshaper if I can't figure it out?

Edit: As for the PWM init sensitivity, the square is now audible most of the turn, so that's good. Haven't tested PWM cv.

Electrically the first two options are the same. There can definitely be a bit of confusion though when wiring switches in general. The way to keep things straight is to envision the switch handle running through the body of the switch. It's a little like a teeter totter. When you push the handle down, the other end goes up and connects the top contact to the middle contact. When you raise the handle back up, the other end goes down, and connects the bottom to the middle contact.

Hello electro-music.com,Matthias & staff!
Little problem. I suppose i have built 4046vco with success,( i used SSM2210)but only issue i got is some ripple(not that firm spike at top of waveform) but more like "distortedlfo" interference.Funny that when i disconnected COARSE pot,issue has gone and signal appeared nice and clean..(with still connected FINE pot).Then i tried with another 100k COARSE pot & shot temp. wire but ripple came back. Ideas..

check your power supply rails see if its got the same ripple on it.
might be coming from another module on the same supply
say an LFO or something with a led flashing at that rate,
if so maybe you are too close to the max current draw for your supply
or not enough decoupling on one of your modules_________________In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any

How i could not mention that i have second VCO with the same deviance! and ripple kept in sync for both actually..So its PSU maybe,strangely but yesterday when i re switched the cab.everything was goodworking but today the ripple cameback.
Sorry Matthias for impeach X-4046 then! Need to go check the PSU.and thanks for all comments!

I am pretty new to modulars and have done very little electronics DIY. I recently bought a secondhand X4046 VCO and the tuning is way off- 1V is more like a major 6th. I tried adjusting the HF and scale trim trimpots according to the documentation here: http://www.birthofasynth.com/Thomas_Henry/Pages/X-4046.html

but could only get it to about a 7th before the scale trimpot ran out- it sounds like it is close to getting to 1V/octave but not quite. I'm using a Minibrute with the arppegiator set on octaves to tune, which might not be ideal but should get me in the ball park at least- my Hertz Donut sounds great with it. What am I missing to calibrate this thing?

The sine out also sounds pretty far off what a perfect sine sounds like. I don't have an oscilloscope, is it even worth playing with the sine trimpots or should I just leave it alone and enjoy my weird sine?

I feel like I just need a slightly lower resistance trimpot for the scale so I can go that little bit further. The trimpots are all Bonems 3296, but all trimpots EXCEPT the scale trimpot have "W 104 / 110 T" printed on top. The scale trimpot has "W 101/ 302B" stamped on top. Should this be the case/is this the source of my problems?

lately i got intrigued by the idea fo re-designing the PCB in order to facilitate eurorack builds w/o wiring. the same way i did it for the new thomas henry projects: one circuit PCB providing MTA-100 footprints, and an additional PCB for the front panel components, accommodating the eurorack standard.

I can see the attraction, but it would preclude those of us with fat fingers wanting to build these projects to the larger standards.

actually not! in the past i did in a ways so that one could just buy and build the circuit PCB, which provides MTA-100 footprints for all controlls, doing manual wiring (so all standrads are possible).
and then there would be an additional PCB for the eurorack folks that would fit straight onto the mta-100 footprints for piggyback mounting...

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